-nen instrumental ending (pl. -inen, dual -nten, partitive pl. -línen). Attested in ambartanen, lírinen, lintieryanen, súrinen, parmanen; see ambar (#2), lírë, lintië, súrë, parma. Tolkien noted that "most nouns have an instrumental in -nen" (PE17:62), a wording suggesting that the form of the ending may vary; given the normal development ln > ld, it is possible that it would appear as *-den when added to a noun in -l (*macilden "with a sword").
Quenya
lírë
song
lírë
noun. song
-nen
most nouns have an instrumental in -nen
téma
row, series, line
téma noun "row, series, line" (pl. témar attested) (TEÑ, Appendix E)
lírë noun "song", stem #líri- in the instrumental form lírinen "in [the] song" or *"by [the] song" (Nam, RGEO:67)